1. Field of the Invention
The invention relates to the positioning of a selected object with respect to a top-dead-center portion of a cylindrical roll. More particularly, the invention relates to an apparatus and method for aligning a casting nozzle with respect to the top-dead-center portion of a rotatable chill roll to rapidly cast continuous metal strip.
2. Description of the Prior Art
Conventional apparatus for aligning a selected object, such as a casting nozzle, over the top-dead-center portion of a cylindrical roll or a wheel to cast metal strip have employed a mirror mounted on a fixed-top surface of a two-legged V-block. The V-block is mounted on the peripheral cylindrical surface of the roll and the mirror reflects an image of the object. The image is viewed through a sighting means and by selectively moving the object to align the reflected image with a reference line, the object is aligned with the top-dead-center of the cylindrical roll.
When employed to align a casting nozzle over the top dead center of a rotatable chill roll to rapidly cast metal strip, the conventional device is well suited for determining the amount of lateral displacement of the nozzle and the twist alignment thereof with respect to the top-dead-center of the chill roll. However, such devices have not been able to adequately measure the degree of tilt offset of the nozzle with respect to the local vertical. As a result, the quench rate, the cross section and the physical properties can vary across the width dimension of the rapidly cast strip. In subsequent manufacturing operations, these variations can adversely affect the use of the metal strip to form end products, such as wound transformer cores or motor cores.
Thus, conventional alignment devices have lacked means to measure the degree of tilt offset of a selected object with respect to the local vertical. As a result, when such devices are employed to align a casting nozzle to rapidly cast continuous metal strip, the strip has had physical properties that are less uniform than is desirable.